1. Field of the Invention
The present invention relates to a wafer transfer apparatus for delivering a wafer to be polished to a wafer holding head and for receiving a polished wafer from the wafer holding head. The present invention also relates to a wafer polishing apparatus to be used for an apparatus for polishing the surface of a semiconductor wafer, and a method for manufacturing the wafer.
The specification of the present invention is based on the Japanese Patent Applications (Japanese Patent Application Nos. 11-69336, 11-69337, 11-69338 and 11-35019), and the content of these Japanese applications are incorporated herein by references.
2. Description of the Related Art
Fine patterning of semiconductor wafers has been developed in recent years as a result of development of highly integrated semiconductor devices. Since fine patterning of the wafers having multilayer structures have been made easy and secure, it is particularly important to planarize the surface of semiconductor wafers as fine as possible in the manufacturing process. Finer planarization of the surface of the semiconductor wafers allows patterning precision to be improved besides making focusing of the exposed light easy when a photolithographic process is used for patterning. In addition, production of the semiconductor wafers can enjoy a low cost because the work efficiency is improved without providing complicated equipments for manufacturing the semiconductor wafers.
A chemical-mechanical polishing method (a CMP method) has been highlighted for this purpose since the method can polish the surface film with a high degree of planarity.
The surface of wafers are mechanically and chemically polished and planarized using an alkaline slurry containing SiO2, a neutral slurry containing SeO2, an acidic slurry containing Al2O3, or a slurry containing other abrasive (these are simply referred as a slurry hereinafter) in the CMP method. A wafer holding head for holding the wafer (a wafer holding head) and a polishing pad are usually disposed in opposed relation with each other in the wafer polishing apparatus for polishing the surface of the wafer, and the wafer is polished by allowing the wafer polishing head to rotate on the polishing pad by pressing the surface of the wafer onto the polishing pad while feeding a slurry.
Although it is desirable that the polishing pad is as planar as possible, its surface is deteriorated to cause decrease of polishing ability (polishing rate) by using it for polishing the wafer, or polishing performance (uniformity of polishing or degree of distribution of the thickness of the remaining film on the wafer) is decreased by causing a little roughness or inclination on the surface of the polishing pad, due to uneven abrasion or clogging of the pad after polishing. Therefore, the polishing pad is subjected to reforming (dressing) for restoring the polishing performance of the polishing pad, by allowing the polishing pad after finishing a wafer polishing process to rotates while allowing its surface to contact a dresser.
The polishing process may be simultaneously carried out with the dressing process as shown in FIGS. 18 and 19. In the first conventional example shown in FIG. 18, the wafer polishing apparatus 250 is provided with a wafer holding head 252 attached at the tip of an arm 251 supported to be able to freely pivot, a slurry feed means 253 for feeding a slurry to a polishing pad 256, and a dresser 254. The slurry feed device 253 directly feeds the slurry to the polishing pad 256 affixed on the surface of a platen 255, and the wafer W held on the wafer holding head 252 is polished by allowing the wafer W to rotate while making contact with the surface of the polishing pad 256. The dresser 254 is, on the other hand, held in rotatable manner with a driving mechanism 257, which is supported on a base 258. The base 258 is also supported to be linearly slidable along the direction indicated by an arrow Y with a guide member 259. The dresser 254 dresses the surface of the polishing pad 256 that has a deteriorated polishing performance after polishing the wafer W. The wafer is polished at a different site from the site for dressing the wafer on the polishing pad 256.
In the second conventional example shown in FIG. 19, the wafer polishing apparatus 300 is provided with three rotatable platens 301 and polishing pads 302 affixed on their surfaces, wafer holding heads 304 provided at the tips of respective two branched arms 303, and dressers 306 that is able to linearly slide along a guide member 305 provided along the radial direction of each polishing pad 302. The arm 303 is supported with a pivot 303a to be able to freely pivot, and the wafers supported with the wafer holding heads 304 are polished with respective polishing pads 302. The surface of the polishing pad 302 is dressed with the dresser 306 that is slidable along the radial direction of the polishing pad 302, while simultaneously polishing the wafer.
The third conventional example of the wafer polishing apparatus comprises an apparatus using a wafer holding head 350 as shown in FIG. 20.
In FIG. 20, the wafer holding head 350 is provided with a head body 353 comprising a top plate 351 and a cylindrical circumference wall 352 fixed to the circumference of the top plate 351, a diaphragm 354 expanded in the head body 353 and comprising an elastic material such as a rubber, a pressure adjustment mechanism 356 for adjusting the pressure in a fluid chamber 358, a disk-shaped carrier 355 fixed on the lower face of the diaphragm 354, and a ring-shaped retainer ring 357 disposed in concentric relation to the outer circumference of the carrier 355.
The carrier 355 and the retainer ring 357 are fixed on a carrier fixing ring 359 and a retainer ring fixing ring 362, respectively, provided on the upper face of the diaphragm 354. The retainer ring 357 is disposed in concentric relation with a slight gap between the outer circumference face of the carrier 355 and the circumference wall 352. The slight gap is provided for suppressing the displacement range of the retainer ring 357 along the radial direction from being too large due to elastic deformation of the diaphragm 354.
The wafer W is affixed on a wafer affix sheet S (an insert) provided on the lower face of the carrier 355, while the outer circumference of the wafer W being locked with the retainer ring 357. The wafer is polished by allowing the wafer holding head 350 and the platen 361 to rotate causing a relative movement, when the slurry is fed onto the surface of the polishing pad 363 and the polishing face of the wafer W from outside of the wafer holding head 350, while allowing the surface of the wafer W to contact the polishing pad 363 affixed on the upper face of the platen 361.
The carrier 355 and the retainer ring 357 has a floating structure in which both members are able to independently displace along the ascending and descending directions by deformation of the diapliragm 354. The pressing pressure of the carrier 355 and the retainer ring 357 onto the polishing pad 363 changes depending on the pressure in the fluid chamber 358 adjusted with pressure adjustment mechanism 356.
While the wafer polishing apparatus as shown in the first and second conventional examples is effective for polishing the wafer, since the wafer polishing process and the dressing process can be simultaneously applied. However, when the wafer is polished with the wafer polishing apparatus as shown in the first conventional example, the slurry is directly fed onto the surface of the polishing pad 256 from outside of the wafer holding head 252. Most of the fed slurry flows out by the centrifugal force applied to the rotating platen 255, forcing to feed a large amount of the slurry for obtaining a sufficient polishing effect. A large amount of an expensive abrasive is wasted without effectively using the slurry. In addition, the polishing debris generated by polishing has been washed out by feeding the slurry on the surface of the polishing pad, also wasting a large amount of the slurry to make the removing method to be high cost with poor efficiency. This problem is common in the wafer polishing apparatus shown in the third conventional example.
Since the dresser 254 occupies a large installation area, a few numbers of wafers holding head 252 are attachable to decrease service efficiency of the apparatus.
In the second conventional example, the dresser 306 has a smaller size than the dresser 302, and is linearly travels relative to the polishing pad 302. Accordingly, it is difficult to uniformly press the entire polishing pad 302, thereby planarization of the surface of the polishing pad 302 has been insufficient.
The fourth conventional example of the wafer polishing apparatus is shown in FIG. 21. The wafer polishing apparatus 400 is provided with a wafer holding head 401 for holding the wafer W to be polished, and a polishing pad 402 affixed on the entire upper face of the platen 403 formed into a disk shape. A plurality of the wafer holding heads 401 are mounted at the bottom of a carousel 404 as a head driving mechanism, which is supported with a spindle 411 and undergoes a planetary motion on the polishing pad 402. It is possible to dispose the center of the platen 403 and the center of rotation of the wafer holding head 401 in eccentric relation with each other.
The platen 403 is horizontally disposed at the center of a base 405, and rotates around the axis line with a platen driving mechanism provided in the base 405. Guide posts 407 are provided at the side of the base 405, and an upper mounting plate (bridge) 409 for supporting a carousel driving mechanism 410 is disposed among the guide posts 407. The carousel driving mechanism 410 serves for allowing a carousel 404 provided below the device to rotate around the axis line.
Bridge supports 412 are disposed so as to protrude upward from the base 405, and a gap adjustment mechanism 413 is provided on the tip of each bridge support 412. A locking member 414 is disposed, on the other hand, above the bridge support 412 in an opposed relation with each other. The locking member 414 is fixed to the upper mounting plate (bridge) 409, and protrude downward from the upper mounting plate (bridge) 409. The space between the wafer holding head 401 and the polishing pad 402 is adjusted by adjusting the gap adjustment mechanism 413 to allow the bridge support 412 to contact the locking member 414. The wafer W is polished by allowing the wafer held on the wafer holding head 401 to contact the surface of the polishing pad 402, while allowing the carousel 404 and the platen 403 to rotate.
While a plurality of the wafer holding heads 401 holding the wafers W are provided, the position of the wafer holding head 401 sometimes finely shifts from the position of the polishing pad 402 affixed on the platen 403, when the thickness of the polishing pad 402 has been reduced by polishing, thereby causing a problem that uniformity and polished planarity of the wafer W become to be poor. However, adjusting the gap adjustment mechanism 413 every time is not only not practical, but also making it difficult to adjust the positioning of the wafer holding head and polishing pad to right and left in a xcexcm unit using the gap adjustment mechanism 413, while suffering the pressing pressure generated during polishing. Also, the positional shift is caused by dimensional changes of the wafer holding head 401, thereby manufacturing excessively polished wafers and insufficiently polished wafers.
Polishing of the wafer W using the polishing apparatus shown in the second conventional example will be described hereinafter. In FIG. 19, the wafer W to be polished is held on each wafer holding head 304 provided at each tip of the two branched arms 303. These wafers W are polished by rotation while they are allowed to contact each pad 302 (referred as respective polishing pads 302a, 302b, and 302c hereinafter) affixed on respective surfaces of three rotatable platens 301. The polishing pads 302a and 302b serve as primary polishing pads, while the polishing pad 302c serves as a secondary polishing pad. These polishing pads 302a, 302b and 302c are dressed with the dressers 306 being able to linearly shift with the guide members 305 provided along respective radial directions. The an 303 is supported with the pivot 303a to be able to freely pivot. The wafer W is subjected to secondary polishing with the polishing pad 302c, after being subjected to primary polishing with the polishing pads 302a and 302b. The Wafer W is attached to and detached from the wafer holding head 304 with a flexible handling robot 307 at a wafer attaching and detaching station 308. The handling robot 307 takes out a wafer W to be polished from a second cassette 309, and attaches the wafer W to the wafer holding head 304 at the wafer attaching and detaching station 308. The wafer W after completing polishing is detached from the wafer holding head 304 with the handling robot 307 at the wafer attaching and detaching station 308, and transferred to a receiving cassette 310.
Since the wafer is attached to and detached from the wafer holding head 304 with the flexible handling robot 307, the construction of the handling robot 307 becomes complicated. Consequently, reliability of handling operation to the wafer W is compromised, or maintenance such as cleaning of the apparatus becomes difficult. Since flexible access range of the handling robot 307 should be enlarged for attaching and detaching a plurality of wafers W to the wafer holding head 304, the handling robot 307 brings about to be large size and complicated, thereby slowing its operation to decrease operation efficiency.
While making the handling robot 307 itself as a wafer attaching-detaching member movable may be contemplated, it causes decrease of reliability and work efficiency because the overall apparatus is complicated, and positioning relative to the wafer holding head 304 becomes difficult.
Accordingly, the object of the present invention is to provide a wafer polishing apparatus that is able to simultaneously and efficiently polish the wafer and dress the polishing pad, and a method for manufacturing the wafer.
For attaining the object above, the present invention provides a wafer polishing apparatus provided with a platen on the surface of which a polishing pad is affixed, and a wafer holding head for allowing one face of a wafer to contact the polishing pad by holding the wafer to be polished, the wafer being polished with the polishing pad by a relative motion between the wafer holding head and the platen, wherein a cylindrical dress ring comprising an abrasive grain layer on its lower part is provided at the outside of the wafer holding head in a rotatable manner while the dress ring is allowed to contact the surface of the polishing pad.
According to the wafer polishing apparatus of the present invention, polishing of the wafer and dressing of the polishing pad are simultaneously carried out, thereby allowing the step number to be decreased and polishing work to be efficient. Dressing of the polishing pad is efficiently carried out while enabling the entire polishing pad to be planarized, by rotating the cylindrical dress ring.
The present invention also provides a method for manufacturing a wafer provided with a platen on the surface of which a polishing pad is affixed, and a wafer holding head for allowing one face of a wafer to contact the polishing pad by holding the wafer to be polished, comprising a polishing step for polishing the wafer with the polishing pad by a relative motion between the wafer holding head and the platen, wherein a cylindrical dress ring comprising an abrasive grain layer on its lower part is provided at the outside of the wafer holding head, and wherein polishing of the wafer and dressing of the polishing pad are simultaneously carried out by rotating the dress ring while allowing it to contact the surface of the polishing pad.
According to the method for manufacturing the wafer in the present invention, the wafer is efficiently polished because polishing of the wafer and dressing of the polishing pad can be simultaneously carried out.
An another object of the present invention is to provide a wafer polishing apparatus and a method for manufacturing the wafer, by which the wafer is efficiently polished by saving consumption of the slurry.
For attaining the above object, the present invention provides a wafer polishing apparatus provided with a platen on the surface of which a polishing pad is affixed, and a wafer holding head for allowing one face of a wafer to contact the polishing pad by holding the wafer to be polished, the wafer being polished with the polishing pad by a relative motion between the wafer holding head and the platen, comprising a slurry pocket, in which a slurry is accommodated and which has an opening at the polishing pad side, formed at a part of a contact portion between the periphery of the portion holding the wafer on the lower face of the wafer holding pad and the polishing pad, and a slurry feed member for feeding the slurry to the slurry pocket are provided.
According to the polishing apparatus of the present invention, the slurry is held with the slurry pocket and the polishing pad, since the slurry pocket accommodating the slurry is formed at a part of the contact portion between the periphery of the wafer holding portion on the lower face of the wafer holding head, and the polishing pad. Consequently, the amount of the slurry flowing out by centrifugal force is diminished even when the polishing pad affixed on the platen rotates. The slurry in the slurry pocket is uniformly fed on the surface of the polishing pad, by allowing the wafer holding pad and the platen to rotate, thus enabling the wafer to be efficiently polished.
The present invention also provides a wafer polishing apparatus provided with a platen on the surface of which a polishing pad is affixed, and a wafer holding head, which holds a wafer to be polished, for allowing the polishing pad to contact one face of the wafer, the wafer being polished with the polishing pad by a relative motion between the wafer holding head and the platen, wherein a slurry holding ring, which is allowed its lower face to contact the polishing pad, and which is disposed so as not to contact the periphery of the wafer holding head, is provided to be rotatable at the outside of the wafer holding head.
According to the wafer polishing apparatus of the present invention, the amount of the flowing out abrasive is reduced by providing the slurry holding ring.
The present invention also provides a method for manufacturing a wafer provided with a platen on the surface of which a polishing pad is affixed, and a wafer holding head for holding a wafer to be polished by allowing one face of the wafer to contact the polishing pad, comprising a polishing step for polishing the wafer with the polishing pad by a relative motion between the wafer holding head and the platen, wherein a slurry pocket, which is open to the polishing pad side, for feeding a slurry is provided at the periphery of the wafer holding portion on the lower face of the wafer holding head, the wafer holding head being allowed to rotate while allowing the lower face of the wafer holding head to contact the polishing pad, and the wafer being polished by feeding a slurry on the polishing face of the wafer and on the surface of the polishing pad while suppressing the slurry fed to the slurry pocket from flowing out.
According to the method for manufacturing the wafer in the present invention, the wafer is efficiently polished using a minimum amount of the slurry, because the slurry is fed into the wafer holding head. Also, flowing out of abrasive due to rotation of the platen is suppressed to reduce the amount of use of the slurry, because the wafer is polished while allowing the wafer holding head to contact the polishing pad so that the opening of the slurry pocket is blocked with the polishing pad.
The present invention also provides a method for manufacturing a wafer provided with a platen on the surface of which a polishing pad is affixed, and a wafer holding head for allowing one face of a wafer to contact the polishing pad by holding the wafer to be polished, comprising a polishing step for polishing the wafer with the polishing pad by a relative motion between the wafer holding head and the platen, wherein a slurry holding ring, which is provided so as to contact the polishing pad and not to contact the outer circumference of the wafer holding head, is disposed at the outside of the wafer holding head, wherein the slurry is fed between the outer circumference of the wafer holding head and the slurry holding ring while allowing the wafer holding head and the slurry holding ring to rotate, and wherein the wafer is polished while suppressing the slurry from flowing out by the slurry holding ring.
According to the method for manufacturing the wafer in the present invention, an efficient polishing is made possible by directly feeding the slurry from the periphery of the wafer, by allowing the slurry to be fed between the slurry holding ring and the wafer holding head, besides being able to suppress consumption of the slurry by reducing the amount of thee flowing out abrasive with the slurry holding ring.
A different object of the present invention is to provide a wafer polishing apparatus and a method for manufacturing the wafer that is able to simultaneously and securely polish a plurality of wafers.
The present invention for attaining the above object provides a wafer polishing apparatus provided with a platen on the surface of which a polishing pad is affixed, and a wafer holding head for allowing one face of a wafer to contact the polishing pad by holding the wafer to be polished, the wafer being polished by a relative motion between the wafer holding head and the platen, comprising: a spindle, which is coupled to the upper part of the wafer holding head, for supporting the wafer holding head in horizontally and freely rotatable manner; and a spindle supporting member provided with a plurality of spindle housings having a cylindrical engage member for engaging the spindle, the spindle comprising a positioning mechanism for positioning the wafer holding head along the axis line direction by changing the relative position against the spindle supporting member.
According to the wafer polishing apparatus in the present invention, plural wafers are securely polished while maintaining a constant polishing condition for each wafer, because each of the plural wafer holding heads can be individually positioned with the positioning mechanism along the axis direction.
The present invention also provides a method for manufacturing a wafer provided with a platen on the surface of which a polishing pad is affixed, and a wafer holding head for allowing one face of a wafer to contact the polishing pad by holding the wafer to be polished, comprising a polishing step for polishing the wafer by a relative motion between the wafer holding head and the platen, wherein a spindle for supporting the wafer holding head in a horizontally and freely rotatable manner engages respective engage members of a plurality of spindle housings provided on the spindle supporting member, wherein the wafer is allowed to rotate while making contact with the polishing pad, and wherein the plural wafers are polished while being individually positioned by positioning the wafer holding head along the axis line so as to change the relative position against the spindle supporting member using a positioning mechanism provided on the spindle.
According to the method for manufacturing the wafer in the present invention, individual wafers are securely polished by fine-tuning the polishing states and polishing conditions, because the wafer holding head can be positioned during polishing the wafer.
A further different object of the present invention is to provide a wafer transfer apparatus and a wafer polishing apparatus, and a method for manufacturing the wafer, by which the wafer can be accurately and securely attached to and detached from the wafer holding head, besides efficiently polishing the wafer.
For attaining the above object, the present invention provides a wafer transfer apparatus for delivering wafers to be polished to wafer holding heads for polishing while allowing the wafer to rotate on a polishing pad, and for receiving the wafer, which is polished by being held on the wafer holding head, from the wafer holding head, provided with: a tray being able to mount the wafer; a tray travelling mechanism for allowing the tray to travel below the wafer holding head; and a wafer attaching-detaching mechanism for attaching the wafer to be polished, which is mounted on the tray, on the lower face of the wafer holding head from below the tray, and for receiving the wafer, which is attached to the wafer holding head and is polished, from the wafer holding head to mount on the tray.
According to the wafer transfer apparatus in the present invention, the wafer is transferred by the tray. The tray travels to below the wafer holding head, where the wafer is attached to and detached from the wafer holding head by the wafer attaching-detaching mechanism provided under the wafer holding head. Since the transfer apparatus and the attaching-detaching mechanism are separated with each other, the mechanisms of respective mechanisms turns out to be more simple. Accordingly, each mechanism can be actually operated at high speed, besides improving reliability and making its maintenance easy.
The present invention also provides a wafer polishing apparatus provided with a platen on the surface of which a polishing pad is affixed, and a wafer holding head for allowing one face of a wafer to contact the polishing pad by holding the wafer to be polished, the wafer being polished by a relative motion between the wafer holding head and the platen, comprising: a tray being able to mount the wafer, a tray travelling mechanism for allowing the tray to travel so as to pass below the wafer holding head, and a wafer attaching-detaching mechanism provided at a position in a space apart from the polishing pad for attaching a wafer to be polished, which is mounted on the tray, on the lower face of the wafer holding head, and for receiving the wafer, which is attached on the wafer holding head and is polished, from the wafer holding head to mount on the tray, the wafer holding head being supported so that the upper part of the polishing pad and the upper part of the wafer attaching-detaching means are movable.
According to the wafer polishing apparatus of the present invention, the wafer is transferred with the tray. The tray moves below the wafer holding head, and the wafer is attached to and detached from the wafer holding head by the wafer attaching-detaching mechanism provided there. Since the transfer mechanism and the attaching-detaching mechanism are independent with each other, each mechanism turns out to be simple, thereby speed-up of the function of each mechanism is realized besides improving reliability with easy maintenance.
The wafer holding head moves above the wafer attaching-detaching mechanism when the wafer is attached to and detached from the wafer holding apparatus, and moves above the polishing pad when the wafer is polished. Since the transfer mechanism and the attaching-detaching mechanism are independent with each other, each mechanism turns out to be simple, and operations of respective mechanisms is stabilized without interfering with each other.
The present invention also provides a method for manufacturing a wafer polishing apparatus provided with a platen on the surface of which a polishing pad is affixed, and a wafer holding head for allowing one face of a wafer to contact the polishing pad by holding the wafer to be polished, comprising a polishing step for polishing the wafer by a relative motion between the wafer holding head and the platen; and a wafer transfer step for delivering the wafer to be polished to the wafer holding head, and for receiving the wafer, which is attached to the wafer holding head and is polished, from the wafer holding head, wherein the tray mounting the wafer to be polished is allowed to travel above the wafer attaching-detaching means while allowing the wafer holding head to travel above the tray, wherein the wafer is polished by allowing the wafer holding head to travel on the polishing pad after attaching die wafer mounted on the tray by the wafer attaching-detaching mechanism on the wafer holding head, and wherein the wafer after polishing is delivered to the wafer attaching-detaching mechanism from the wafer holding head to mount the wafer on the tray.
Since the transfer mechanism and the attaching-detaching mechanism are independent with each other according to the method for manufacturing the wafer, each mechanism turns out to be simple, thereby speed-up of the function of each mechanism is realized besides improving reliability with easy maintenance.
The wafer polishing apparatus and the wafer-attaching-detaching mechanism is disposed with a distance apart, besides the wafer holding head moves above the wafer attaching-detaching mechanism when the wafer is attached to and detached from the wafer holding head, and the wafer holding head moves above the polishing pad when the wafer is polished. Consequently, each mechanism turns out to be simple, and operations of respective mechanisms is stabilized without interfering with each other.